January 25, 2010

Evaluating the Traditional Arguments for God

Kant famously classified traditional arguments for the existence of a divine being into three categories: ontological, cosmological, and teleological. Very few, if any, philosophers today think that any of these forms of argument is conclusive. However, some philosophers do believe that a cumulative case for the existence of a divine being can be made out from these arguments. Atheist colleagues often respond that "three leaky buckets won't hold water any better than one." However, this reply assumes that the traditional arguments don't show anything at all. Specifically, those who respond this way are often assuming that the arguments are straightforwardly invalid (that is, that they commit formal errors of reasoning).

I myself believe that the traditional arguments can contribute to a cumulative case. I think that a person who has certain background beliefs/information might be perfectly rational in accepting the existence of God on the basis of these arguments alone. However, I am willing to admit that for most people the traditional arguments are insufficient. In short, I only want to make the modest claim that each of the arguments has something positive to contribute to our overall evaluation of the plausibility of theism.

Let us begin with teleological arguments. Nearly everyone agrees that the world appears to have elements of purposiveness. That is, it often seems as if there is some sort of grand plan. This appearance is created by natural beauty, and also by the sophistication of certain natural (especially biological) systems.

Now, in the absence of evidence to the contrary, it is reasonable to believe that things are as they seem. For instance, my stapler looks red. Most philosophers would agree that it is prima facie reasonable to believe that my stapler is red on the basis of its looking that way, unless I have some evidence to the contrary. This is despite the fact that if I were wearing red glasses, or was under red light, or my lens had been dyed red, or I was being deceived by the Cartesian demon, the stapler might look just the same to me. (What it means for the stapler to really be red is, of course, another matter entirely.) These are all more or less extravagant hypotheses, and if I have no evidence that one of them is true, then I should just proceed on the assumption that things are as they appear.

So we arrive at this general maxim: other things being equal, we should assume that things are as they appear.

When combined with the appearance of purposiveness in the natural world, this maxim yields the result that, other things being equal, we ought to assume that there are elements of the natural world which have a purpose. Yet it is hard to see how anything could have a purpose in the absence of one who purposes, and this all men call 'God.'

Now, many atheists implicitly accept this line of argument, but deny that other things are equal. This at least seems to be what is going on with those who claim that primitive people were (or are) reasonable in believing in a divine being, but there is surely no excuse now that modern science has explained everything. Individuals familiar with modern science are in possession of evidence that we are wearing red glasses (so to speak). When posting on the teleological argument a while back, I argued that this line of argument was ineffective.

Teleological arguments show that belief in a divine being is prima facie reasonable. The structure of the argument, as I conceive it, is like this:

The universe appears to have purpose.

It is prima facie reasonable to believe that things are as they appear.

Therefore,

It is prima facie reasonable to believe that the universe has purpose.

Where there is purpose there is one who purposes.

Therefore,

It is prima facie reasonable to believe that someone has a purpose for the universe.

I think (1) and (2) are relatively uncontroversial. (4) might be a little more controversial (Aristotle, for instance, seems to have rejected it). Also, the argument relies on an inference pattern like this:

It is prima facie reasonable to believe that p.

p entails q

Therefore,

It is prima facie reasonable to believe that q.

I think a few philosophers might regard this inference pattern as invalid, but most would accept it. In general, whatever level of justification a proposition possesses is transmitted to its logical consequences. So teleological arguments use fairly uncontroversial premises, but get only the weak result of prima facie reasonableness, not the strong result of truth.

Cosmological arguments start from the basic idea that "why is there anything at all?" is a reasonable question to ask. Most people seem to agree with this basic idea.

There are a number of ways of turning this question into an argument for a divine being. Some versions become quite complicated, especially those that allow that the universe might not have a beginning in time. However, if we assume that the universe did have a beginning (since, on the basis of discoveries in physics, most people now believe that it did), we can state the argument quite simply, as I did a couple months ago:

Every contingent entity or event has a cause.

There are no causal loops and no infinite causal regresses.

Therefore,

There is at least one necessary (i.e. non-contingent) cause (and this all men call 'God').

Now, this argument has the virtue of actually having an existence claim (rather than a reasonable belief claim) as its conclusion. However, its premises are more controversial. Still, the premises seem at least plausible. Cosmological arguments can establish the existence of a first cause deductively, but their premises are merely plausible and certainly open to question.

Ontological arguments are trickier. Here's an example of an ontological argument that is at least clearly valid:

If the existence of a divine being is possible, then it is necessary.

A divine being exists.

Whatever is actual is possible.

Therefore,

Necessarily, a divine being exists.

Now, some readers are probably wondering how on earth this type of argument is supposed to contribute to a case for the existence of a divine being. After all, it takes the existence of a divine being as a premise!

Well, a key weakness of teleological and cosmological arguments is that they don't establish anything like a being with the traditional divine attributes. Teleological arguments establish the reasonableness of believing in someone who creates (or at least directs) the world for certain purposes, and cosmological arguments establish the existence of a necessary being. I understand the contribution of ontological arguments to be that they contribute to the unity or coherence of the theistic hypothesis - that is, they show that something like the traditional God is a good candidate for the roles carved out by the previous arguments.

In order to see how this is supposed to work, let's start by examining premise (1). Premise (1) is supposed to be a non-trivial 'analytic' truth. (I put 'analytic' in scare quotes to remain agnostic as to whether there is a non-vague analytic-synthetic distinction.) That is, it is supposed to be the case that the definition of 'divine' implicitly includes necessary existence. One can run the argument above with any adjective whose definition implicitly or explicitly includes necessary existence. However, if premise (2) is to be plausible, we should have some kind of simple definition which entails necessary existence and we should already have reason to believe that something exists which has some of the other properties entailed by the definition. This is basically the project of traditional philosophical theology: give some simple definition like 'pure actuality' (Aristotle) or 'a being greater than which none can be conceived' (Anselm) and try to show that it entails (a) necessary existence, and (b) some collection of attributes we already know something has.

If this project is successful, we can exploit it in two ways. First, if we can show that the simple definition entails that a divine being would have the properties necessary to satisfy the teleological and cosmological arguments (i.e. would have the sorts of purposes we observe, and would be a first cause of the sort of universe we are in), then we will have reason to believe that something fitting that definition exists. It would have the theoretical benefit of unifying the theoretical postulates the two arguments led us to Second, religious believers (who we have mostly left out of our discussion so far) believe on the basis of (alleged) revelation that God has certain attributes - e.g. omnipotence, omniscience, etc. If it can be shown that those properties follow from a simple definition which also entails necessary existence, then this will contribute greatly to the theoretical unity of the theory.

In sum, I believe that (assuming someone can make good on my hand-waving promises of a philosophical theology) these three arguments together help to show that theism is a theory with a high degree of internal coherence which allows one to endorse some independently plausible metaphysical theses. If the atheist merely wants to defend the consistency of her position, all she has to do is deny one of the premises of the cosmological argument (e.g. by saying that the Big Bang is contingent but doesn't need a cause), or argue that some alternative entity (e.g. the universe itself) can be the first cause; neither the teleological argument nor the ontological argument establishes the existence of a divine being. If, however, the atheist wants to show that her theory is superior to the theist's - so that the theist ought rationally adopt it - then, for each argument, she will have to do one of the following:

Undermine it (by providing a defeater for the prima facie entitlement established by the teleological argument, or a disproof of one of the premises of the cosmological argument)

Provide an alternative hypothesis which exemplifies theoretical virtues to a greater degree than the theistic hypothesis and provides an entity to play the role the argument requires.

Perhaps these tasks can be accomplished, but it is certainly not so trivial as to render the traditional arguments irrelevant.Posted by Kenny at January 25, 2010 7:30 PM

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Comments

On the transmission of prima facie reasonability, you write, "I think a few philosophers might regard this inference pattern as invalid, but most would accept it. In general, whatever level of justification a proposition possesses is transmitted to its logical consequences."

Whether or not most would accept that inference form (and I am not so sure that they would), I think most philosophers should not accept it. For instance, each premise in Zeno's paradox of motion (the one where you keep halving the distances) is prima facie reasonable, but, surely the paradoxical result (e.g. motion is impossible) is not prima facie reasonable.

More generally, we often invoke entailments of a specific view to demonstrate that the reasonableness of the view is merely prima facie. While I agree that there is some restricted version of that form of inference that may be regarded (appropriately) as valid, it is not fair game to simply invoke arbitrary instances of it.

(I haven't looked carefully at the instances of it you rely on, nor have I looked carefully at whether the upshot of your discussion depends on this in any crucial way).

Also, I think you should be careful about what is built into the claim: "the universe appears to have purpose".

Presumably, you want a reading of this that is not rendered true simply by there being any appearance of purposeful activity whatsoever (since many atheists would happily grant that human activity is often purposeful). But, at the same time, you presumably also want a reading that does not presuppose that the universe appears to have one overarching purpose (since this is a much stronger claim than would be commonly accepted). Rather, I assume you want something like: some natural (i.e. non-human) activity appears to be purposeful. And, really, you'd want "natural" there to rule out at least some animal activity, I'd imagine.

Suppose we nail down "natural" appropriately: Then, I guess what I am thinking is that, at the end of the day, your argument would look something more like:
There appears to be purposeful activity in the natural world.
So, it is prima facie reasonable to believe that there is purposeful activity in the natural world.
So, for each such activity A, it is prima facie reasonable to believe that something (apart from people/animals) has a purpose for A.

But maybe I am misunderstanding what you intend to be building into the argument.

On your first comment: I think this depends on how we understand the prima facie qualifier. I intend something like the following:

Evidence E provides renders a proposition p prima facie reasonable =df. an agent in possession of E and not in possession of any other relevant evidence would be reasonable to believe p.

In this sense, I think it is true that the fact that Zeno's paradoxes are entailed by plausible premises renders the paradoxes prima facie reasonable. However, to say that they are paradoxes is simply to say that it is hard to imagine someone grasping the proposition in question without having compelling evidence of its falsehood. This, I think, is why we have the intuition that nothing could make the paradoxes prima facie reasonable.

On your second comment: my exposition of each of the arguments was rather imprecise, because I wanted to evaluate the overall argumentative strategy, rather than a specific version of the argument. Incidentally, I think your reconstruction is a good one, and it might help explain how primitive people would be reasonable in accepting polytheism. We can then conceive of classical (mono)theism as a unifying hypothesis. But you are right that unless it seems to us that there is a Grand Plan for the universe as a whole (and I imagine that this is pretty controversial) it will be hard to use this strategy to establish that the same entity has purposes in each case of apparent purposiveness. I imagine that nearly everyone agrees that there are some events which seem purposive (as long as we emphasize seem strongly enough) which are not easy to explain in terms of human or animal intentions, but fewer people would say that there seems to be a Grand Plan.

What do you make of the following argument:
1) No outright/manifest contradiction is ever prima facie reasonable to believe.
2) Arbitrary instances of the T-schema are prima facie reasonable to believe.
3) The empirical premise in the Liar paradox is prima facie reasonable to believe.
4) If (1)-(3), the argument form you indicate is not valid.
5) So, the argument form you indicate is not valid.

The way I used 'prima facie reasonable' above was relative to some evidence. Now, if something is a manifest contradiction then, by definition, it wears the evidence against it 'on its face', as it were. So I would consider the fact that the statement is obviously contradictory to amount to a defeater of the reasonableness of believing it (that's why the entitlement is ONLY prima facie).

Consider this case. Suppose A has never studied any logic, but knows that B is a logic professor. B shows A the two premises in the argument for the Liar Paradox, and tells A, "a certain proposition, p, follows logically from these premises." It would be prima facie reasonable for A to believe that p is true. But then A is told that p is the proposition that (say) 2=1. The reasonableness of A's belief is defeated. (It may be even better to suppose that B shows A the premise that arithmetic is decidable, and explains what that means.)

Perhaps 'prima facie reasonable' was a poorly chosen phrase for what I'm trying to get at.

Regarding the teleological argument, you have a major fallacy. it is in your point 2

2. It is prima facie reasonable to believe that things are as they appear.

That doesn't hold for three reasons.

1. There are things (such as living creatures) which appear to have purpose but which in fact don't, they are the result of undirected evolutionary purposes. Therefore there are things in the universe which have the appearance of purpose (of design) but where that appearance is an illusion. Therefore it is unsafe to make an assumption with regard to the general case of the universe as a whole concerning a matter where you already know of a contrary case with regard to a constituent part of it.

2. A cognitive illusion commonly suffered by humans is mistakenly to discern agency where in fact there is none, where there is only randomness. This has been demonstrated in innumerable psychological experiments. Therefore in the case of seeing purpose in the universe (or anything else), it is not prima facie reasonable to believe that things are as they appear. Instead, it is necessary to investigate the matter with the greatest of care to ensure that you are not being deceived by the cognitive illusion.

3. You have not explained in what way the universe would look different if it did not have purpose, and so you have provided no means of discerning between a universe with or without purpose. Remember, in the past people thought the sun went round the earth - because it looked as if it does. But how would it have looked if it looked as if the earth rotated?

I myself believe that the traditional arguments can contribute to a cumulative case. I think that a person who has certain background beliefs/information might be perfectly rational in accepting the existence of God on the basis of these arguments alone. However, I am willing to admit that for most people the traditional arguments are insufficient. In short, I only want to make the modest claim that each of the arguments has something positive to contribute to our overall evaluation of the plausibility of theism.

This is a logical fallacy. Five fallacious arguments are collectively no more convincing than they are individually.

I suspect that you are thinking in terms of Bayesian probability theory, where various pieces of evidence can be used to modify one's estimate of the probability of some circumstance. Richard Swinburne makes this attempt in his book The Existence of God, but since he doesn't appear to understand the circumstances in which Bayes' theory is valid, he makes a complete pig's ear of the argument.

On teleology: none of your comments show that my premise 2 is "a major fallacy." You are, rather, arguing in exactly the way I anticipated when I said "many atheists implicitly accept this line of argument, but deny that other things are equal." That is, the considerations you introduce contribute nothing to a debate over whether the argument shows that it is prima facie reasonable to suppose that things are as they appear; rather, your considerations contribute to showing that it is not all things considered reasonable. Your comments completely ignore the distinction between prima facie reasonableness and all things considered reasonableness, which I made in the post. (At another point I expressed this by saying "other things being equal." On what exactly is meant by this, see the exchange with Lewis above.) Your first consideration is analogous to saying that we are under red light, and your second consideration is analogous to saying that we are wearing red glasses. Neither of these cases show that it wasn't initially (i.e. before we had evidence of red light or red glasses) reasonable to suppose that things were as they appeared.

As to your third consideration, do you think ancient people were irrational to believe that the sun goes around the earth? Or do you just think that we have new evidence now which shows that this is false? These two claims are importantly different for purposes of the present discussion.

At any rate, none of the three considerations actually undermine my modest claim that the argument gives a reason to suppose that theism is prima facie reasonable. Rather, they accept that claim and try to show that it is nevertheless not all things considered reasonable. This is the point: if you are trying to claim that things are not as they appear, you need some evidence. In the absence of such evidence, it is reasonable to think that things are as they appear.

It would take a lot more than what's in this post to show that theism is all things considered reasonable and, as I acknowledged, "for most people the traditional arguments are insufficient" - that is, most people in the developed world today are epistemically situated in such a way that they would not be reasonable in believing in God without further evidence or considerations not mentioned in this post. You can't blame me for not establishing things I never claimed to establish.

On cumulative cases: It is absolutely true that "Five fallacious arguments are collectively no more convincing than they are individually." I discussed this very objection in my first paragraph: "this reply assumes that the traditional arguments don't show anything at all. Specifically, those who respond this way are often assuming that the arguments are straightforwardly invalid." Now, what I have claimed is that the arguments are not invalid/fallacious. Rather, I have claimed that they do show something. It's just that they don't demonstrate the existence of God from self-evident principles. If you want to claim that they are invalid/fallacious, please point out the specific fallacy committed. In order to do this you have to be careful to note (1) that the conclusion of the teleological argument, as I conceive it, is not the existence of God, but the prima facie reasonableness of belief, and (2) that there is a difference between a fallacious argument and an argument with false premises.

Now, none of this has anything to do with Swinburne or Bayesianism. Everyone, whether they believe in Bayesianism or not, agrees that sometimes multiple sources of evidence can collectively contribute justification to a conclusion. Furthermore, everyone (including Swinburne) agrees that fallacious arguments don't contribute to justification. I have tried, in this post, to provide suggestions (not rigorous proofs) in the direction of three claims:

(1) Theism allows us to say that things are as they appear in some circumstances where atheism does not.
(2) Theism allows us to adopt some plausible metaphysical principles which are difficult to accommodate in an atheistic theory.
(3) Theism is a unified and internally coherent hypothesis.

If you want to claim that the arguments are actually fallacious, you need to show that even if you grant me the premises, I don't get those three conclusions. You haven't said anything that even remotely suggests an argument in that direction.

However, the point I think you are trying to make is that these three points don't necessarily contribute to the overall plausibility of theism. For instance, the contribution of (1) would be undermined if there was independent reason (independent of the debate between theism and atheism!) to suppose that in this case things are not as they appear. The contribution of (2) would be undermined if it were shown that the premises are not so plausible after all, or that atheism can accommodate them just as easily. Finally, (3) would be undermined if it was shown that some atheistic hypothesis was actually more unified and internally coherent than theism.

It is not obvious that any of the contributions is undermined in any of these ways. That is not to say that they can't be undermined, but, as I said in concluding my post "it is certainly not so trivial as to render the traditional arguments irrelevant."

I never said that it is a rule that things are as they appear. What I said was that in the absence of evidence to the contrary it is reasonable to believe that things are as they appear. Because we don't have all the evidence, there are many things which are reasonable for us to believe despite the fact that they are (unbeknownst to us) false.

I think that we have to accept my principle on general epistemological grounds, and so I think it would be valid even if the cases where things are not as they appear outnumber the cases where they are. This is because if we don't assume it we will never get the project of inquiry off the ground. So the idea is that we always have to start out by supposing that things are as they appear, and then adjust that assumption in light of further evidence.

Where did you get this list of fallacies? Not one of these is a formal fallacy - that is, none of them is a flaw in the structure of an argument. (1) and (2) could be instances of something like the Fallacy of Decomposition, where a generalization over a class is mistakenly applied to an individual member of the class, but they are not in general. Furthermore, while the fallacy of decomposition renders an argument deductively invalid, the argument may still be valid on probabilistic grounds. For instance, if I know that most lottery tickets are losers, then I know that the one I bought is probably a loser.

It is more accurate to classify your 'fallacies' as common sources of false premises.

Still they are all inaccurate as applied here. (1) and (2) are inapplicable because, as I said, I didn't argue from "things are most often as they appear" to "things are, in this case, as they appear." The application of (3) to my argument amounts to begging the question. I have heard (3) called the 'anthropomorphic fallacy.' It is the error of attributing human characteristics to things that don't have those characteristics. But that presupposes that the things don't have those characteristics, which is precisely the question that is at issue. What you need is an argument for the claim that they don't have those characteristics. The fact that you need such an argument strengthens my (albeit modest) claim that teleological arguments cannot simply be dismissed.

What I said was that in the absence of evidence to the contrary it is reasonable to believe that things are as they appear.

And I say that because of the many cognitive illusions under which we labour, that is an invalid conclusion. Moreover, science has progressed in the way and to the extent that it has in part by refusing to accept that conclusion, and instead investigating matters in more depth, so that we can find out whether or not things are as they appear.

Jonathan - Let me further clarify something. What I intended to claim in my version of the teleological argument is that in the absence of evidence to the contrary we should believe that things are as they appear, and things appear to have purpose. Now, we could have either of two types of evidence to the contrary: (1) evidence that things are some other way than the way they appear, or (2) evidence that appearances of this sort are usually unreliable. You have been claiming that we have evidence of both type (1) and type (2). So far, I have not disputed this claim because I am still trying to make you understand that all my argument says is that if we didn't have that evidence it would be reasonable to believe that things are as they seem. When you respond by pointing to that kind of evidence, you implicitly concede this point. So, you implicitly admit that the argument I am actually making is not only valid but sound (you accept the premises and the conclusion). You then claim that I am making some other argument which is invalid. I don't know what the invalid argument you think I'm making is, but if the argument I actually make in the text above is invalid then the sort of evidence you are bringing up doesn't make a difference. My argument says that in order to undermine the reasonableness of belief in God on the basis of teleological arguments, you need to provide evidence of the sort you yourself are trying to provide. If you disagree, then why are you trying to provide that kind of evidence?

I don't see any benefit to disputing your evidence unless we first get this point clear.

Science hasn't rejected the principle that we should start out by assuming that things are as they appear. Science has progressed by trying to gather further evidence for or against the veracity of appearances in particular cases and has found that in many cases appearances are misleading. However, if we START from the assumption that appearances are misleading, we can never get science going. Galileo had to assume that the rate at which balls appear to roll down ramps is (roughly) the rate at which they actually roll down ramps. The same goes for any scientific experiment. Even when you read a complicated instrument of some sort, you have to assume that the instrument says what it appears to say. We start by assuming that things are more or less the way they appear, and then we adjust that assumption as far as the evidence warrants. Not only do we have to start with the assumption that things are (roughly) the way they appear, but we have to keep that assumption in at least some cases. If scientists concluded that nothing was as it appeared, they wouldn't be able to continue, because they wouldn't be able to make any observations.

Let me further clarify something. What I intended to claim in my version of the teleological argument is that in the absence of evidence to the contrary we should believe that things are as they appear, and things appear to have purpose.

That's the logical fallacy of cherry-picking. If you only select for consideration only evidence in a particular direction and ignore the rest, then you can reach whatever conclusion you choose.

It would be fallacious for precisely the reason you indicate if I claimed that my argument showed that God exists, but I never said anything of the sort. The conclusion of my argument was that someone who had certain evidence - namely, the appearance of purpose - and didn't have other relevant evidence would be reasonable to believe that someone (or ones - see the discussion with Lewis, above) has purposes for things. Now, you might criticize me for posting an argument for an uninteresting conclusion, but you haven't given any reason to think that my argument is invalid or that any of the premises are false. In fact, your cherry-picking complaint acknowledges the central claim that I set out to prove: the appearance of purpose is evidence for the existence of God. All by itself it's far from conclusive, but it's relatively rare for just one source of evidence to conclusively decide any interesting question.

I think that basically the same is true of the cosmological argument. If you understand just how modest the conclusions I am trying to draw are, then I think you will have to acknowledge that the argument works. (In fact, in our previous discussion, you acknowledged that the argument was valid, but pointed out that the argument is limited by (1) the fact that the premises are merely plausible, not proven, and (2) the fact that it doesn't establish any of the traditional attributes of God. I agree with both of these claims.)

I don't make any strong claims in support of my ontological argument - just that if all that mumbo jumbo really can be turned into something coherent (and it is not obvious that it can't) it will contribute to the simplicity and internal coherence of the theistic hypothesis.

It doesn't matter what the conclusions are, or how modest you believe the claims you are making to be. If your premises are false or unsound, then your conclusions cannot be relied on, no matter how impeccable the formal logic is which leads from the premise to the conclusion.

Logic is easy, but fundamentally useless by itself. If you want to construct an argument, you have to ensure that your premises are sound.

By the way, you also claim that your first premise is "uncontroversial", but it is unsustainable unless you have some means of distinguishing how a universe with purpose would look as compared to a universe with no purpose. Since we are unaware of the existence and properties of any universes other than the one we are in. We are similarly unable to determine what other kinds of universes are possible from among those we can imagine, and since we are agents who have purpose in what we do, we may find it impossible even to imagine what a purposeless universe might consist of (that is, if it is different from the one we happen to occupy at present).

In the absence of this means of distinguishing between a universe with purpose and one without (in just the same way as ancient man was unable to distinguish between how things would look if the sun went round the earth and how they would look if the earth rotated), you cannot make the claim that the universe looks purposeful, still less state that the claim is "uncontroversial".

Kenny,
You write, "Consider this case. Suppose A has never studied any logic, but knows that B is a logic professor. B shows A the two premises in the argument for the Liar Paradox, and tells A, "a certain proposition, p, follows logically from these premises." It would be prima facie reasonable for A to believe that p is true. But then A is told that p is the proposition that (say) 2=1. The reasonableness of A's belief is defeated. (It may be even better to suppose that B shows A the premise that arithmetic is decidable, and explains what that means.)"

I think you need to be careful about the distinction between:
1) It being prima facie reasonable for A to believe that [the proposition indicated by B] is true.
and
2) For the proposition indicated by B (call it p), it being prima facie reasonable for A to believe that P is true.

Note that in your case you suggest that it is reasonable for A to believe p before he finds out that p is the proposition that 2=1. It seems to me that you are conflating situations (1) and (2).

Look back at the formulation of the form of inference in your post itself. There you lay it out as:
1) It is prima facie reasonable to believe that p.
2) p entails q
Therefore,
3) It is prima facie reasonable to believe that q.

Your proposed case (with A and B and the proposition that 2=1), does not look to be a case in which it is prima facie reasonable for A to believe that 2=1 (even if we grant that it is prima facie reasonable for A to believe that arithmetic is decidable, or the like). Rather, it is a case in which it is prima facie reasonable for A to believe that the proposition indicated by B is true.

Here is why this matters in general, and also why it matters for your particular application:
Suppose that, relative to one's evidence E, it is prima facie reasonable to believe that Divine command theory is true. The truth of Divine Command theory entails that God does not forbid things because they are wrong. But, relative to the same E, it may well _not_ be prima facie reasonable to believe that God does not forbid things because they are wrong.

For the teleological argument, if my evidence makes it prima facie reasonable to believe that the universe has a purpose, and if the universe having a purpose entails that there is some extra-universal (i.e. physically disembodied) agent, it may be that the latter is not prima facie reasonable to believe.

2 It is prima facie reasonable to believe that things are as they appear.

I can see why someone would accept 2. If things appear red, square, wet, etc..., it is reasonable to believe they are red, square, wet, etc... without further information but that's because we're either dealing with sensible qualities or we're dealing with things that have a distinctive look. Does _having a purpose_ have a distinctive look? Seems to me that _having a purpose_ has no more distinctive look than _being born in Jerusalem_ has a distinctive look (to rip off Anscombe). So, I'm not entirely sure I know what you could mean by saying that the universe appears to have a purpose. Maybe you mean 'There's evidence that the universe has purpose'? We say things like 'The defendant appears to be guilty', meaning that if we look at all the available evidence there is a sufficiently strong probability of guilt. So, is premise 1 just 'We have good evidence of purpose'? If _that's_ what 1. means, shouldn't that be a conclusion?

Jonathan - I think we've had about as much useful exchange as we can within the parameters of this post. However, some of the points you've raised, especially in your first comment are, I think, interesting and important ones. I hope to address some of them in future posts.

Lewis - I think you may be right that there is a problem here. Many philosophers do believe that justification (of the sort necessary for knowledge) is closed under known entailment, though that view has some known problems. However, there may be even bigger problems for views that allow this with lesser epistemic statuses.

The intuition I was going for can be put in Bayesian terms (though I have some anti-Bayesian readers) by saying that if one believes that p with degree of confidence x, and has not previously entertained q, and then discovers that p entails q, then q should inherit degree of confidence x, since P(q|p)=1. In the sorts of cases we are discussing, we get some complexity because there are some independent considerations as to the degree of confidence we should have in q.

Now, in saying that it was prima facie reasonable, I meant to note the possibility that there might be a defeater coming in from another direction. I meant to claim that teleological considerations provide weak evidence - but evidence none the less - for some sort of 'extra-universal' agent.

It seems to me that your divine command theory case rests on there being other relevant evidence.

Let me fall back to my redness example. Suppose a piece of fruit seems red to me. Now, this alone renders me prima facie reasonable in supposing that it IS red. But suppose I further know that the only red fruit that could possibly be in my fruit basket is an apple. So I am prima facie reasonable in believing it's an apple. However, if I have some other evidence that it's not an apple, that could defeat the prima facie assumption. Furthermore, if I'm sufficiently confident that it can't be red unless its an apple, the evidence that it's not an apple could even undermine the reasonableness of my belief that it's red.

If you don't like the term 'prima facie reasonable' it seems to me that there is SOME significant epistemic status a proposition can have which can be substituted in the above paragraph to make it true. Do you agree with that? Whatever that status is, it's what I'm saying the appearance of purpose gives to theism (or at least belief in some sort of extra-universal intelligence or intelligences).

First, you haven't proposed closure of this epistemic status under known entailment, simply under entailment. This is one reason it may be far too strong.

Second, and relatedly, it is odd that you would frame the point in "bayesian terms" when your case involves acquired knowledge of a logical relationship and the introduction of a new hypothesis (since logical learning and the problem of new theories are two long-standing thorns in the Bayesian's side).

Third, a minor nitpick, I think you want to say that q should have a credence of _at least_ x (after all, in many cases, when p entails q, it is also possible that q and not p).

Fourth, I do want to be pressing a point that I think still stands: given a body of evidence E, and a pair of propositions P, Q, such that P entails Q, an agent with E may or may not know that P entails Q. My contention is that it is possible that, for some agent A, i) P has some positive epistemic status (due to its appearing to be true) and ii) Q has some negative epistemic status (due to its being evidently false), while, for another agent, A', i) P lacks the positive epistemic status and ii) Q retains its negative epistemic status.

My thinking is that A's situation is possible when the entailment is unknown, but, for A', who recognizes the entailment, Q's negative epistemic status undermines the positive status A otherwise would have had.

At any rate, I am at least not sure that the positive epistemic status will leak through to the entailed claim.

Put another way: if the situations I have in mind would all involve some sort of evidential shift upon discovery of the entailment, then, there would be a relevant evidential shift in the case of the teleological inference, and it is not clear the form of argument you cite is relevant.

If you don't want to answer the points that is entirely your business.

One further point is about your usage of words. You are using "looks", "seems" and "appears" as if they are perfect synonyms. They aren't, and you need to be vary careful that you don't load your word usage with more than one meaning and thereby engage in another logical fallacy.

Your example was "For instance, my stapler looks red. Most philosophers would agree that it is prima facie reasonable to believe that my stapler is red on the basis of its looking that way, unless I have some evidence to the contrary."

The giveaway is that you are in fact using a different word here: "looks" instead of "seems". The stapler looks red because light of a specific range of wavelengths is scattered from the stapler and some of it is incident on your retina. So we have a directly observed phenomenon.

But you then elide from "looks" to "seems" and "appears", and you say "Nearly everyone agrees that the world appears to have elements of purposiveness. That is, it often seems as if there is some sort of grand plan. This appearance is created by natural beauty, and also by the sophistication of certain natural (especially biological) systems."

In this second case, you are not making a direct observation, but drawing an inference. Purpose is something that we infer from observed phenomena, it is not something we observe directly.

And we now know that in the case of observing the sophistication of biological systems that the inference of purpose is not justified.

If you want to avoid this kind of mistake, then you need to word everything more tightly. What you then get is as follows:

1. The universe can be inferred to have purpose

2. It is prima facie reasonable to believe that things are as they are observed to be.

As you can see, point 1 is now dealing with inference, and point 2 with direct observation, and they have no logical connection that allows you deduce point 3 from points 1 and 2. But this was hidden by your sloppy use of words.

Next is the Cosmological argument. The flaws in the argument as you have presented it are as follows:

1. It is not clear that every contingent entity or event has a cause. For instance, it is not known whether the radioactive decay of a particular atom has a cause. All we know is that there are statistical rules that we can deduce concerning the proportion of atoms of a particular type that will decay in a certain period of time.

2. We cannot at this time be certain that there are no causal loops or infinite regresses. We do not know enough about the universe to be able to make this a definite premise on which to base a line of argument.

3. Even if the first two premises turn out to be true, all that can be deduced is the existence of at least one non-contingent cause. Nothing more can be deduced about the cause other than that it happened (at least once). It is a mistake to make any other claim at all about it. It most certainly is unjustified to call it "God", since this associates the first cause with all sorts of properties (omnscience, answering prayers etc) which are part of the common understanding of the meaning of the word "God", but which are unconnected with the deduction just made. It really was very naughty of Aquinas to tag "and we call this cause 'God'" on to the end of Aristotle's version of the cosmological argument.

With regard to the ontological argument, there is no reason to accept either of the two premises.

The first premise has the following problems

1. The characteristics of a "divine being" are not specified, therefore we cannot know what it is we are assenting to.

2. Without knowledge of the definition of a divine being, it is not possible to say whether the conclusion is a valid one.

3. Since the first premise contains a line of reasoning (an initial premise linked to a conclusion), it ought to be broken down into its constituent parts so we can examine the reasoning more closely.

The second premise is simply asserted without support.

Ontological arguments in general have grave problems with them, for instance Gaunilo's Islands and Douglas Gasking's ontological proof of the nonexistence of God. If by consistently following a line of reasoning you can reach multiple contradictory conclusions, then there must reductio ad absurdam be a flaw in the logic, even if the precise nature and location of the flaw is not known.

So, in total you have presented three flawed arguments. As you agreed earlier, it doesn't matter how many flawed arguments you have, they don't become more convincing for being put together.

"I think Kenny is adopting the principle that, ceteris perebus, if it seems to S that P, S is prima facie reasonable in believing that P.

And then I think he is also assuming that it seems (at least, to many individuals) that the universe has purpose (or weaker: that some non-human/non-animal originated events are purposive)."

Hey Lewis,
Right, but my point was that there are (basically) two ways to read the argument and both readings were problematic. Suppose we distinguish observational seemings from evidential seemings. An OS will involve awareness of some property or properties that indicate F-ness. An ES will be evidence that there is F-ness where there is no restriction to appearances, looks, and the like. You could say that some object seems square or seems far, and that could be observational seemings. You could say that it seems the guy cheated on his taxes, and that's not going to be observational.

Plausibly, if it seems to S that p in either sense, it will be prima facie rational for S to believe p. The problem was this. Consider:
(1) The universe appears to have a purpose.

Which sense of "appears" are we dealing with? I say that there's no appearance property or properties that could serve as grounds for the judgment that (1) is true. Could (1) be true if we're talking about appears in the evidential sense? Sure, but then (1) is equivalent to:

(1') There's evidence that the universe has a purpose.

Okay. What is it? So far as I can tell, it's not some mark, indicator, appearance, look, or any such thing that we're aware of. (1') looks like it needs justification if it is going to offer any justification. I'd say the same for (1).

Sorry I haven't kept up on the comments. I was having technical difficulties trying to get my wireless working on campus this afternoon. I will try to process all of these comments and post some kind of response tomorrow.